Location: Food Processing and Sensory Quality Research
2023 Annual Report
Objectives
Determine the effects of intensive aeration production systems parameters on fillet flavor and texture.
Approach
Catfish is the major finfish aquaculture species produced in the United States, accounting for 51 percent of US aquaculture food fish sales in 2013. However, consumption of US grown catfish products has dwindled from its maximum of 319 million pounds in 2003 to almost half at 161 million pounds sold to consumers in 2012. This reduction in consumption of U.S. catfish has been the result of increased competition by cheaper imports. A method to counter this trend would be to produce a consistently higher quality product having less variability in its taste, texture, and color. The most pressing quality problems, as identified by the Catfish Industry, are the incidence and variability of off flavors and texture of the fillets.
Because of the increased competition and decrease in consumption of US catfish there is a need to increase production efficiencies to reduce price to consumers. Toward this goal, a number of intensive pond production systems have been developed and adopted by the catfish industry over the past 10 years. This has resulted in a wide variation of production conditions, which may induce variability in product quality. The proposed research will examine the differences and variability in texture and flavor quality of the fillets resulting from the different pond management parameters for three pond production systems - conventional, split-pond, and intensively aerated. Differences found in quality attributes will assist in the refinement of catfish management decisions to produce a higher quality, more consistent product needed for increased consumer acceptance.
Progress Report
This project is currently operating at 26% of its scientist capacity. As such, progress has been slow due to these staffing issues. In support of the project’s only objective under National Program 106 (Aquaculture) and Component 1 (Improving the Efficiency and Sustainability of Catfish Aquaculture), ARS scientists have been researching to determine how intensive pond aeration production systems affects fillet flavor and texture. ARS scientists conducted a study to compare the off-flavor compounds and textural differences of catfish fillets harvested from split-ponds and intensively aerated ponds. They gathered samples from both ponds at two different points throughout the year, in addition to the time of harvest. The samples were examined for 2-methylisoborneol (MIB) and geosmin compounds (which cause off-flavor), as well as environmental factors such as temperature and rainfall. Scientists conducted two passive methods of determining off-flavor incidents and analyzed the results. They found no significant differences among any of the parameters for either pond type. After collecting samples and running tests, the researchers discovered that the herbicide Diuron 4L had been utilized to manage microbes responsible for generating off-flavor chemicals. Consequently, these results were not suitable for publication. FPSQ scientists conducted texture profile analysis to compare physical fillet differences between pond types. There were no significant differences found.
ARS researchers in New Orleans, Louisiana conducted a study to investigate alternative methods of geosmin (an "earthy" off-flavor) uptake in fish. In collaboration with an industry partner and stakeholders, they examined the sources of off-flavor in fillets to deduce that these fillets can absorb geosmin via the gastrointestinal system. This notion had never been considered before as a potential route of exposure and uptake. To validate this hypothesis, the team used rainbow trout as a model system and provided the fish with a dietary supplement of geosmin for four weeks, while maintaining them in a continuous flow of fresh water. Data revealed that more substantial doses of geosmin in the fish diet correlated with higher concentrations in the fillets – providing evidence for a dietary route of exposure not previously considered when dealing with off-flavor in aquaculture. This discovery opens up avenues for future research to explore ways of limiting this flavor in farmed fish species.
In the second phase of this collaborative research with an industry partner, investigators fed trout higher doses of geosmin for a longer duration of time. In this phase, scientists used a more sensorially active form of geosmin. Increased dietary geosmin exposure resulted in higher levels of the off-flavor compound in fillets. These results validated the leading evidence provided by the previous study and provided additional information about the effects of feed-borne geosmin levels and time of exposure on accumulation in fillets. This system of imparting off-flavors into fillets at higher levels allows for new sensory threshold research.
In research led by AquaRange Research LLC/Bozeman Fish Technology Center and the Louisiana Universities Marine Consortium (LUMCON), ARS scientists in New Orleans collaborated to explore the potential of using invasive carp as a sustainable aquaculture feed ingredient for catfish. This investigation was designed to determine whether carp can serve as a viable replacement for essential sources of protein and fat such as Menhaden fishmeal. Over two seasons, researchers from AquaRange and LUMCON collected invasive carp from three distinct regions: two in Louisiana and one in Illinois. The objective of this study was to analyze how location and season affect the composition and nutritive value of the carp. These researchers conducted extensive research to explore the effects of carp composition on catfish growth and composition. Their studies found that diets containing carp fishmeal and oil produced catfish fingerlings with comparable growth, feed intake, feed efficiency, and proximate composition to those given menhaden diets. Additionally, the researchers examined ingredient interactions to enhance soybean meal digestibility. These findings may open up a new market for invasive carp, providing an alternative to the depleting harvests of menhaden while benefiting Louisiana’s river ecosystems and native fish populations. The ARS scientists played a critical role in this research by performing sample preparation, defatting, fatty acid analysis, and amino acid analysis.
This project has made significant advancements in modernizing facilities and infrastructure. The research unit has procured recirculating aquaculture systems to raise fish onsite. Moreover, the unit is renovating an existing building to house and process the fish.
Accomplishments
1. ARS researchers uncover the role of dietary geosmin in creating 'muddy' off-flavors in fish. The naturally occurring chemical geosmin is responsible for “muddy” or “earthy” off-flavors in fish. This presents a major quality issue for fish producers across the aquaculture industry. Up to this point, nearly all off-flavor mitigation research has focused on waterborne geosmin. ARS researchers in New Orleans, Louisiana, demonstrated leading empirical evidence that geosmin can accumulate in fish fillets through their diets. By spiking feed with geosmin, researchers established a new system to impart the off-flavor compound into the edible portions of fish. Now, ARS scientists can use dietary exposure to study off-flavor prevention and correction in catfish and other species, as well as effects on sensory quality.
Review Publications
Dupre, R. A., Ardoin, R., Trushenski, J., Jackson, C., Grimm, C., Smith, B. 2023. Dietary uptake of geosmin in Rainbow Trout (Oncorhynchus mykiss). Aquaculture. 571, 739458. https://doi.org/10.1016/j.aquaculture.2023.739458
Murillo, S., Ardoin, R., Prinyawiwatkul, W. 2023. Factors influencing consumers’ willingness-to-try seafood byproducts. Foods. 12(6), 1313. https://doi.org/10.3390/foods12061313.
Murillo, S. Ardoin, R., & Prinyawiwatkul, W. 2023. Consumers’ acceptance, emotions, and responsiveness to informational cues for air-fried catfish (Ictalurus punctatus) skin chips. Foods. 12(7), 1536. https://doi.org/10.3390/foods12071536
